Fast image acquisition system and method using pulsed light illumination and sample scanning to capture optical micrographs with sub-micron features

ABSTRACT

An optical inspection system for detecting sub-micron features on a sample component. The system may have a controller, a camera responsive to the controller for capturing images, an objective lens able to capture submicron scale features on the sample component, and a pulsed light source. The pulsed light source may be used to generate light pulses. The camera may be controlled to acquire images, using the objective lens, only while the pulsed light source is providing light pulses illuminating a portion of the sample component. Relative movement between the sample component and the objective lens is provided to enable at least one of a desired subportion or an entirety of the sample component to be scanned with the camera.

STATEMENT OF GOVERNMENT RIGHTS

The United States Government has rights in this invention pursuant toContract No. DE-AC52-07NA27344 between the U.S. Department of Energy andLawrence Livermore National Security, LLC, for the operation of LawrenceLivermore National Laboratory.

FIELD

The present disclosure relates to systems and methods for opticalinspection of various components, workpieces and optics, and moreparticularly to an optical inspection system and method which makes useof controlled, short duration light pulses to help capture clear, highresolution micrographs of a component, workpiece or optic, and withoutthe need to repeatedly stop movement of the component, workpiece oroptic while each micrograph is being captured.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

In order to achieve a high power laser system, high laser damageperformance optics are a key component. In order to make high laserdamage performance optics, one needs to know what causes the damage.Based on calculations, the size of damage precursors are often on theorder of 100 nm. In order to capture these submicron sized featuresusing an optical microscope, high numerical aperture (“N.A.”) (>˜0.6)objective lenses are suggested. Currently, optical micrographs arecaptured using medium N.A. (˜0.35) objective lenses, which are notsufficiently sensitive to capture the sub-micron sized features. Yet,even with high N.A. objectives, these small features are often sparselydistributed over the area of an optic. As such, this requires theinspection of a large area, relative to the size of the features thatone is attempting to detect.

One conventional method for capturing a plurality of images from largearea samples involves taking an image of a portion of the sample, movingthe sample to a new location, taking another image of a differentportion of the sample, and repeating this sequence until a plurality ofimages (often a large of plurality of hundreds or more) are obtainedwhich cover all areas of the sample. Typically, using this conventionalmethod, it may take an hour or more to acquire optical micrographs ofeven just a one square centimeter area, even with a medium N.A.objective (˜0.35). With this conventional inspection method, and using amedium N.A. objective, the detection of sub-micron scale features issimply not possible. To enable detection of sub-micron features, highN.A. objective lenses are suggested which, however, lead tosubstantially longer time to image the same area.

Hence, it would be highly valuable to be able to obtain sub-micronresolution optical micrographs so that sparsely distributed sub-micronfeatures, which may be distributed over a large area, are capturedwithin a reasonably short time frame. This capability would help addressthe challenge of identifying the stochastic damage precursor, andpotentially enable the user of even higher power laser systems. Forindustry, this capability of more rapidly identifying sub-micronfeatures on a sample, in a significantly shorter period of time, isexpected to reduce costs by substantially reducing the time for largearea optical inspection operations. This would be extremely beneficialin a number of industries, and particularly with semiconductormanufacturing operations.

In order to detect sub-micron scale features, commercially availableTransmission Electron Microscopy (TEM) or Scanning Electron Microscopy(SEM) instruments are used since electrons provide higher resolutionthan photons. However, these techniques have limitations. For TEM,samples should be thin enough (<500 nm) to transmit electrons, whichrequires complex sample preparation processes. Furthermore, with the TEMmethod, it is not practical to study the stochastic behavior (e.g.,discrete laser damage), which requires inspection of a large samplearea. For the SEM technique, there is the sample size limitation aswell. Another significant limitation of the SEM technique is that itonly captures surface features; sub-surface features cannot be detected.

Photoluminescence (PL) is another 2D optical mapping technique which candetect sub-micron features. However, the PL technique is usable onlywhen the features being detected are PL sensitive.

In some applications, high resolution images of a large sample area areneeded. One specific example where it is especially important to capturehigh resolution micrographs is with large area optics used in connectionwith lasers at the National Ignition Facility (NIF), which is operatedby the Lawrence Livermore National Laboratory. High resolutionmicrographs are needed to locate sub-micron size damage precursors inthe optics used with the NIF lasers. However, previously used imagingsystems are not practical for capturing high resolution opticalmicrographs of large area optics (e.g., optics having a diameter of 2.0inches or larger, such as 40 cm×40 cm) within a reasonable time frame.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

In one aspect the present disclosure relates to an optical inspectionsystem for detecting sub-micron features on a sample component. Thesystem may comprise a controller, a camera responsive to the controllerfor capturing images, an objective lens able to capture submicron scalefeatures on the sample component, a pulsed light source and a camera.The pulsed light source generates light pulses. The camera is controlledto acquire images, using the objective lens, only while the pulsed lightsource is providing light pulses illuminating a portion of the samplecomponent. Relative movement between the sample component and theobjective lens is provided to enable at least one of a desiredsubportion or an entirety of the sample component to be scanned with thecamera. In another aspect the present disclosure relates to an opticalinspection system for detecting sub-micron features on a samplecomponent. The system may comprise an electronic controller, a camera,an objective lens, a beam splitter, a pulsed light source and a stage.The camera may be responsive to the controller for capturing images, andmay include an aperture. The objective lens is used in connection withthe camera to capture submicron scale features on the sample component.The pulsed light source is controlled to generate light pulses eachhaving a duration of no longer than one microsecond. The beam splitterdirects light pulses at least one of having passed through the samplecomponent, or having been reflected from the sample component, towardthe aperture of the camera. The camera is controlled to acquire images,using the objective lens, only while the pulsed light source isproviding light pulses illuminating a portion of the sample component.The stage supports the sample component, wherein at least one of thestage or the camera is moved to create relative movement between thesample component and the camera.

In still another aspect the present disclosure relates to a method forperforming optical inspection of a sample component to detect sub-micronfeatures associated with the sample. The method may comprise generatinga plurality of light pulses directed at the sample, wherein each lightpulse has a duration of no more than one microsecond. The method mayalso include directing the light pulses through an objective lens havinga numerical aperture which provides a resolution sufficient to identifysubmicron features. The method may further include using a camera toimage portions of the sample while at least a subplurality of the lightpulses are being generated, and while the sample is being moved relativeto the camera. The method may further include using the camera to createa plurality of images of subportions of the sample to reveal one or moresubmicron features associated with the sample.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

FIG. 1 is a high level block diagram of one embodiment of a system inaccordance with the present disclosure for capturing high resolutionmicrographs;

FIG. 2a is an example of a micrograph captured using a prior art systemwhile the sample is held stationary, and illustrating that a specificfeature is clearly identifiable;

FIG. 2b is an example of a micrograph obtained with a prior art systemwhile the sample is moving and a continuous light signal is beingapplied, which illustrates the significant blur that is introduced whichessentially eliminates detection of the feature shown in FIG. 2 a;

FIGS. 3a, 3b and 3c are illustrations of three micrographs obtained atthree successive periods in time using the system and method of thepresent disclosure, which illustrates the high resolution and clarity ofeach image, and a slight degree of overlap between the three imageswhich is useful when stitching the images together to form a larger,composite image;

FIG. 4a is an enlarged illustration of a micrograph obtained using thepresent system and method to help illustrate that a degree of imageshift does not affect the quality and resolution of the obtainedmicrograph;

FIG. 4b is a diagram illustrating the shift occurring during a lightpulse, when using the present system and method, is equal to thevelocity of movement of the sample multiplied by the time duration ofthe light pulse being used;

FIGS. 5a and 5b illustrate a degree of movement of a specific visiblefeature on the sample from a first image capture (FIG. 5b ) of thesample to a second image capture (FIG. 5a ) of the sample, when thevelocity of movement of the sample is 1 mm/s;

FIG. 6 illustrates a composite image created from a large plurality ofindividual micrographs obtained using the system and method of thepresent disclosure, where each square “tile” in this example is aseparate micrograph having dimensions of 200 μm×200 μm; and

FIG. 7 is a high level flow chart illustrating various operations thatmay be performed using the methodology of the present disclosure tocreate a composite image from a plurality of independent, highresolution micrographs, such as that shown in FIG. 6.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

The present disclosure relates to various embodiments of a system andmethod for collecting a plurality of optical micrographs from a samplehaving a large surface area, in a substantially reduced time whencompared to previously developed imaging systems. First, in order totake images from a large area, the sample may be translated using amovable stage. To capture images with high resolution, an objective lenswith a high N.A. is located over the sample. To take opticalmicrographs, illumination is provided to illuminate at least asubportion of the surface area of the sample. Still images ofsubportions of the surface area of the sample are obtained while thesample is translated, and while at least subportions of the sample areilluminated with short duration light pulses. With this approach, highresolution images showing sub-micron features can be captured while thesample is continuously moving. Due the short time of illumination,images delivered to a camera are captured as clear, still images. Thecontinuous movement of the sample, while images are captured “on thefly”, enables a large plurality of micrographs to be obtained for arelatively large surface area within a time period that would not bepossible with pre-existing imaging systems.

It will be appreciated that at the present time, in the NationalIgnition Facility (NIF), it takes about 1 full hour to image a single,two square centimeter sample using an objective lens with a N.A. of0.35. The present system and method, using an unmodified, commerciallyavailable camera operating at 100 frames per second camera, can imagethe same area in about 10 seconds or less. The system and method of thepresent disclosure therefore scans a sample with a dramaticallyincreased speed, and more particularly with an increase of about twoorders of magnitude in speed (i.e., about 360 times faster). With thepreviously used imaging technology, and a N.A. of 0.35, sub-micronfeatures are not captured. With previously used imaging technologymaking use of an objective lens having a higher N.A., sub-micronfeatures can be captured, but the acquisition time for a ˜1 cm² samplewould be about 25 hours, which is not practical since a typical samplesize may be about two inches in diameter or larger. However, the systemand method of the present disclosure can image a 1 cm² sample in aboutfour minutes, and with sub-micron resolution. Scans in even less timethan this are achievable with resolution which is still better thanpreviously used imaging systems.

One embodiment of an image acquisition system 10 in accordance with thepresent disclosure is illustrated in FIG. 1. A high magnificationobjective lens 12 is located over a sample component 14 (hereinaftersimply “sample 14”). The objective lens may have a high numericalaperture (N.A.), for example preferably at least about 0.5 or higher,and more preferably about 0.6 or higher.

The sample 14 may be any form of workpiece or optical component where itis important to be able to identify submicron features or defects on asurface, or even inside, the sample. The sample 14 is supported on astage 16 which is moved along X and Y axes (and optionally even along aZ axis) using a stage translation subsystem 18. In one specificimplementation the stage translation subsystem 18 may be a motorizedstage translation subsystem driven in accordance with electrical controlsignals, either in a closed loop or open loop control arrangement,applied to a suitable motor (e.g., DC stepper motor). The electricalposition control signals may be generated by an electronic controller orcomputer 20, which for convenience will be referred to simply as“electronic controller 20”. The electronic controller 20 may include abuilt-in memory 22, which alternatively may be an independent componentwhich is accessible by the electronic controller 20. The memory 22 inone implementation is a non-volatile memory (e.g., RAM, ROM, etc.) andmay contain control software 24 for generating the electrical positioncontrol signals used by the stage translation subsystem 18 forcontrolling motion of the stage 16, and thus motion of the sample 14during scanning operations.

The electronic controller 20 is also in communication with at least onecamera 26 having an aperture 26 a for imaging the sample 14. The camera26 may take several different forms, but in one example the camera 26may be a CMOS sensing device or a charge coupled device (“CCD”). Theelectronic controller 20 may use its control software 24 to control “On”and “Off” operation of the camera 26. The electronic controller 20 mayalso be in communication with a pulsed light source 28, and may use thecontrol software 24 to also control on/off operation of the camera 26 insynchronization with light pulses produced by the pulsed light source28. In either event, the pulsed light source 28 creates a series ofshort duration light pulses 28 a, typically on the order of less thanabout 1 μs in duration, and more preferably about 10 ns or shorter induration, which are transmitted through the sample 14 in a “transmissionmode” of operation, and which are synchronized with “On” and “Off”operation of the camera 26, to thus enable a series of images to becaptured by the camera 26. The light pulses 28 a may be re-directed by abeam splitter 30 into an aperture 26 a of the camera 26. Optionally, apulsed light source 28′ may be located elevationally above the objectivelens 12 if the pulsed light is being used in a “reflection mode” ofoperation. In the “reflection mode”, the pulsed light 28 a′ is reflectedfrom an upper surface 14 a of the sample 14 and redirected by the beamsplitter 30 back into the aperture 26 a of the camera 26. The lightpulse duration may be the same regardless if the transmission mode orthe reflection mode of operation is used. With the transmission mode ofoperation, as noted above, the light pulses 28 a pass through the fullthickness of the sample 14, entering its lower surface 14 b and exitingthe upper surface 14 a.

In another embodiment, both of the transmission and reflection modes areused. In this embodiment both of the light sources 28 and 28′ are used.The camera 26 may capture the light from one of the light sources, forexample from light source 28, while a second camera 27 having anaperture 27 a is used to capture light from the other light source, forexample reflected light from light source 28′. When the objective lens12 is shared, both (reflection and transmission) can be taken at thesame time. For this approach, the light pulses can be split by the beamsplitter 30 and can be delivered to two beam paths (light pulses 28 a onone beam path and light pulses 28 a′ on the other beam path). In thiscase, the light sources 28 and 28′ operate at the same time.

Another embodiment contemplated by the present disclosure involvesputting two objective lenses in separate locations, where each isassociated with a separate pulsed light source and a separate camera.One objective lens, its associated pulsed light source and itsassociated camera, are form one subsystem which is used in thereflection mode. The second objective lens, its associated pulsed lightsource and associated camera, form a second subsystem which is used inthe transmission mode. In this configuration, just the sample stage 16is shared and the pulsed light sources can be operated at differenttimes. The pair of cameras and the pair of pulsed light sources shouldalso be synchronized in operation. This embodiment can offer additionalflexibility. For example, a 50× objective lens+532 nm wavelength (pulsedlight source) may be used for the transmission mode of operation, whilea 100× objective+355 nm wavelength (pulsed light source) may be used forreflection (or photo luminescence images).

As illustrated by arrows 32 in FIG. 1, a field of view, which is thearea that the objective lens 12 can see or image, is smaller than thesample 14 size. Therefore, in order to see/take micrographs from a largesample area, the sample 14 is scanned/translated in the X and Y planesusing the stage translation subsystem 18. With previously developedsystems, In order to capture optical image information from the regionof interest, image acquisition is required through the objective lens 12(e.g., reflection mode) or through the sample 14 (e.g., transmissionmode). Since optical image information is delivered to the camera 26during the entire duration that illumination is being provided, if thesample 14 is moved/vibrated/shifted during the illumination time, theimage information is also moved/vibrated/shifted, and therefore, thecaptured image is shown as blurred. For comparison, an image capturedwhile the sample is perfectly stationary is shown in FIG. 2a , and thevarious features, such as feature “F” in FIG. 2a are clearly detected inthe micrograph. But in FIG. 2b , the movement of the sample while animage is captured, and while a continuous illumination signal isprovided, produces an image in which the features of the micrograph aresignificantly blurred, as indicated by the arrow “A” in FIG. 2b . Infact, virtually none of the features visible in FIG. 2a are visible inthe micrograph of FIG. 2b . Therefore, in general, when a continuouslight source (e.g., lamp) is used to take micrographs of a large area ofa sample, movement of the sample is stopped for a short time periodbefore capturing the image, to avoid any vibration from the previousscanning. This is because, the shift of the sample during theillumination is proportional to the scanning speed (v)*the illuminationtime or exposure time (τ). Therefore, such a result is not acceptablefor obtaining still micrographs on a 10 μm scale because the resultingmicrograph will be blurred.

With the system 10, however, when a nanosecond duration light pulse fromone of the light sources 28 or 28′ is used, (e.g., τ=10 ns) to providethe illumination, and the camera 26 is controlled to capture themicrograph during the short illumination duration, the resulting shiftis only 10 nm (i.e., 1×10⁻⁸ m), even when the sample 14 is scanned atv=1 meter per second. In other words, when a short light pulse of ananosecond scale is used for illumination, a large area sample can betaken in a substantially reduced time with excellent image quality(i.e., where there is no noticeable shift in the sub-micron scale)because of the ability to capture clear, non-blurred micrographs withouthaving to stop movement of the sample 14 prior to, and during, captureof each scan (i.e., each micrograph).

FIGS. 3a-3c illustrate three successive micrographs obtained using thesystem 10 of the sample 14, with the micrograph first obtained at t=t₀,(FIG. 3a ), the second obtained at t=t₀+1/N (FIG. 3b ), and the thirdobtained at t=t₀+2/N (FIG. 3c ). For example, with a typical prior artsystem making use of a typical CCD exposure time of about 10milliseconds (with some variation for how bright the continuous lightsource is), and with a scanning speed of 1 mm/s (i.e., 1×10⁻³ meter persecond), it was found that the resulting images are significantlyblurred in the 10 μm scale. On the contrary, when using the system 10with the same parameter (i.e., scanning speed of 1 mm/second), but withthe pulsed light source 28 with a pulse duration of 10 ns, the blur is0.01 nm (1 mm/sec×10 ns), which is virtually zero. The clarity of theimages obtained using the system with this pulse duration of 10 ns canbe seen in FIGS. 3a-3c , which also evidence a small degree of overlapwhich is useful for stitching the images together to form a largercomposite image.

FIG. 4a illustrates a single micrograph taken under the above conditions(i.e., 1 meter per second sample 14 movement and light pulse of 10 ns),where the features on the sample 14 are clearly delineated even in spiteof movement of the sample. FIG. 4b is a diagram which helps toillustrate that the shift is related to the velocity of movement of thesample 14 multiplied by the time duration of the light pulse used (T).

FIGS. 5a and 5b illustrate optical micrographs taken under a pulsedlight using the system 10, while the sample 14 was translated at 1 mm/s.In this example, the micrograph of FIG. 5a was taken 100 ms after themicrograph of FIG. 5b . The scale is 10 μm. A particle circled withcircle “C” in FIG. 5b has moved 100 μm since the scanning speed was setto 1 mm/s. The micrographs shown in FIGS. 5a and 5b were obtained usingthe transmission mode. The sub-micron feature identified by circle C isdetectable by the system 10 when a 50× objective lens (e.g., objectivelens 12) is used.

FIG. 6 shows a stitched image 50 collected of the sample 14 using thesystem 10. Each square grid or “tile” 52 represents a separatemicrograph having dimensions of 200 μm×200 μm. Specific features, suchas feature 54, are formed over a plurality of contiguous micrographsonce the stitching is accomplished. The overall stitched image 50 can beobtained in a small fraction of the time that would otherwise berequired with previous systems that require repeatedly stopping andstarting movement of the stage during the image acquisition process, andeach of the micrographs have excellent clarity.

In summary, an important feature of each of the various embodiments ofthe present disclosure is the use of light sources which produceultrashort duration light pulses, rather than continuous light sources.By replacing the continuous illumination of a light source used withpreviously developed image acquisition systems, along with the importantneeded changes to enable synchronizing operation of the camera with theultrashort duration light pulses, the present disclosure can be employedto take high resolution micrographs without stopping movement of thesample 14. For preliminary data, the images shown in FIGS. 4a, 5a, 5band 6, were taken with a commercially available pulsed, nanosecond lightsource. Such light sources are available from a number of sources. Onesuitable, commercially available light source is the Superk CompactSupercontinuum Laser, available from NKT Photonics, Inc. of Portland,which is a pulsed white light source which can be operated at arepetition rate=1 to 20 kHz, and with a pulse duration<2 ns).

The stage 16 and the stage translation subsystem 18 are alsocommercially available components. One such source of a suitablemotorized stage is Aerotech, Inc. of Pittsburgh, Pa., available as modelPlanarDL-200XY, which has a maximum speed of movement of 750 mm/s and atravel length of 200 mm. The objective lens 12 is also a commerciallyavailable component. The micrographs illustrated in the presentdisclosure were obtained with a 50× objective lens from Mitutoyo Corp.of Takatsu-ku, Kawasaki, Kanagawa, Japan, which has a N.A. of 0.55 and aworking distance of about 13 mm. One camera that may be used with thesystem 10 is a CCD device available from Thorlabs, Inc. of Newton, N.J.,as model DCU224C, which has a max capture rate (i.e., frame rate) of 15frames per second (15 fps). For experiments with the system 10, thecapture rate was set to N=10 Hz for the camera 26 and the light source28, and the scanning speed was set to 1 mm/s. The images (FIGS. 4a, 5aand 5b , as well as the micrographs used to construct the image 50 ofFIG. 6) were captured every 100 ms (1/N) while the sample 14 wasscanned. The raw image captured of each micrograph in FIGS. 5a, 5b and5c is 291 μm×233 μm, and there are overlaps between images, which can beused when stitching the individual images together to make a larger,composite image.

Referring to FIG. 7, a high level flowchart 100 is shown illustratingvarious operations that may be performed using the system 10. Atoperation 102 a light pulse of suitable duration (e.g., nanoscaleduration pulse) is generated from the light source 28 (or 28′). Atoperation 104, the camera 26 may be used to obtain an initial imageduring generation of the light pulse. At this point the sample may bestationary or may even be moving. The electronic controller 20 maycontrol the camera 26 (and/or camera 27) to acquire the image(s) atprecisely the time that the light source 28 (or pulsed light source 28′)is/are being fired to emit a light pulse. The electronic controller 20may control the camera 26 (and/or camera 27) in an open loop fashion, inaccordance with a programmed pulse sequence of predetermined “On” and“Off” time durations. Alternatively, the electronic controller 20 mayuse a closed loop control arrangement with feedback provided back fromthe camera 26 and/or the pulsed light source 28 (or pulsed light source28′) to the electronic controller 20, to achieve an even greater degreeof control over the image acquisition operation. Still further, theelectronic controller 20 may be responsive to a triggered output fromthe pulsed light source 28 (and/or pulsed light source 28′) which tellsthe electronic controller when the pulsed light source is being fired sothe electronic controller is able to control the camera 26 (and/orcamera 27) to acquire an image at exactly the proper time. All of theabove control methodologies are considered to be within the scope of thepresent disclosure, and the electronic controller 20 is not limited touse with any one of these control schemes.

The electronic controller 20 may also control the stage translationsubsystem 18 to control movement of the sample 14 at the desired rate ofmovement. Optionally, the stage translation subsystem 18 may becontrolled by a separate controller, in which case the separatecontroller may (or may not) also be in communication with the electroniccontroller 20. Movement of the sample 14 may be controlled in a rasterscanning pattern (i.e., linear, back and forth pattern), or in any otherdesired pattern, which may depend in part on the shape of the sample 14being inspected. At operation 106 movement of the sample 14 may beinitiated, or may continue, at a selected rate of movement. The selectedrate of movement may vary significantly, and may be based at least inpart on the duration of the light pulses being used. Scanning speeds maybe determined at least in part by a capture rate of the camera beingused (capture rate=N), as well as a field of view of the objective lensbeing used (field of view=w), and where a maximum scanning speed (v)=w/N(shown in FIG. 1). If the scanning speed is slower than v, then therewill be overlapped regions in images.

At operation 108 the camera 26 is controlled by the controller 20 toobtain another image while the light source 28 (or 28′) is illuminatingthe sample 14 and while the sample is moving. At operation 110 a checkmay be made to determine if the entire sample 14 has been scanned. Ifthis check produces a “No” answer, then operations 106-110 may berepeated until the check at operation 110 produces a “Yes” answer. Whenthis occurs, at operation 112 the collected images (i.e., micrographs)may optionally be stitched together to form a composite image bysuitable stitching software. Such stitching software is widelycommercially available. One example of suitable stitching software isImageJ, which is an open source Java image processing program.

The system 10 and method of the present disclosure thus enables clear,excellent quality micrographs to be obtained in dramatically reducedtimes for any sample size. The larger the sample being imaged, thegreater the time savings which will be realized when using the system10. The system 10 can be implemented using widely commercially availablecomponents. The system 10 and its methodology are also readilyimplementable in Photoluminescence (PL) 2D mapping systems, when theneed is to detect specific features that are PL sensitive. The system 10is also expected to find significant utility in semiconductormanufacturing applications and in any application where examination andidentification of sub-micron scale features on a workpiece, component oroptic is needed for evaluation or quality study purposes.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

What is claimed is:
 1. An optical inspection system for detectingsub-micron features on a sample component, the system comprising: acontroller; a camera responsive to the controller for capturing images;an objective lens able to capture submicron scale features on the samplecomponent; a pulsed light source which generates light pulses; and thecamera being controlled to acquire images, using the objective lens,only while the pulsed light source is providing light pulsesilluminating a portion of the sample component; and wherein relativemovement between the sample component and the objective lens is providedto enable at least one of a desired subportion or an entirety of thesample component to be scanned with the camera.
 2. The system claim 1,wherein the pulsed light source provides light pulses each having aduration of not longer than one microsecond.
 3. The system of claim 1,wherein the pulsed light source provides light pulses each having aduration of no longer than 10 ns.
 4. The system of claim 1, furthercomprising a movable stage for supporting the sample component andenabling movement of the sample component.
 5. The system of claim 4,wherein the movable stage comprises a motorized stage.
 6. The system ofclaim 1, wherein the objective lens comprises a numerical aperture of atleast 0.5.
 7. The system of claim 1, wherein the camera is turned on andoff in accordance with a frequency of between 1 Hz and 20 kHz.
 8. Thesystem of claim 1, further wherein the system includes software forstitching separate images together to form a larger composite image. 9.The system of claim 1, further comprising a beam splitter for directingthe light pulses from the pulsed light source toward an aperture of thecamera after the light pulses have passed through the sample component,while the camera is turned on to capture an image.
 10. The system ofclaim 1, further comprising a beam splitter for redirecting light pulsesreflecting off of the sample component back toward an aperture of thecamera while the camera is turned on to capture an image.
 11. An opticalinspection system for detecting sub-micron features on a samplecomponent, the system comprising: an electronic controller; a cameraresponsive to the controller for capturing images, the camera includingan aperture; an objective lens able to capture submicron scale featureson the sample component; a pulsed light source which is controlled togenerate light pulses each having a duration of no longer than onemicrosecond; a beam splitter for directing light pulses at least one ofhaving passed through the sample component or having been reflected fromthe sample component, toward the aperture of the camera; the camerabeing controlled to acquire images, using the objective lens, only whilethe pulsed light source is providing light pulses illuminating a portionof the sample component; and a stage for supporting the samplecomponent, wherein at least one of the stage or the camera is moved tocreate relative movement between the sample component and the camera.12. The system of claim 11, wherein the stage comprises a movable stage.13. The system of claim 11, wherein the objective lens comprises anobjective lens having a numerical aperture of at least 0.5.
 14. Thesystem of claim 11, wherein the light source is pulsed on at a frequencyof between about 1 Hz to 20 kHz.
 15. The system of claim 11, wherein thelight source is pulsed on for a time duration of no longer than 10 ns.16. The system of claim 11, wherein the camera comprises at least one ofa CMOS device or a charge coupled device (CCD).
 17. The system of claim12, wherein the electronic controller controls movement of the stage.18. A method for performing optical inspection of a sample component todetect sub-micron features associated with the sample, the methodcomprising: generating a plurality of light pulses directed at thesample, wherein each said light pulse has a duration of no more than onemicrosecond; directing the light pulses through an objective lens havinga numerical aperture which provides a resolution sufficient to identifysubmicron features; using a camera to image portions of the sample whileat least a subplurality of the light pulses are being generated, andwhile the sample is being moved relative to the camera; and using thecamera to create a plurality of images of subportions of the sample toreveal one or more submicron features associated with the sample. 19.The method of claim 18, wherein the camera acquires the plurality ofimages in accordance with a frequency of from 1 Hz to 20 kHz.
 20. Themethod of claim 18, wherein directing the light pulses through anobjective lens comprises at least one of: directing the light pulsesthrough a full thickness of the sample, and then through the objectivelens; or directing the light pulses through the objective lens towardone surface of the sample, and then directing a reflected light pulsefrom the surface back through the objective lens.